Since the beginning of agriculture, the cultivation of desirable plants has been hampered by the associated growth of weed plants which tend to sprout in close proximity to cultivated plants, and which compete with the latter for space and nutrients. In addition, any exposed ground adjacent to the plants causes the unwanted loss of water from the soil, depriving the plants of needed moisture. In response to these problems, one of the methods commonly resorted to in order to discourage the growth of weeds and to retain soil moisture involves the distribution around the plants of loose covering material of a type capable of preventing light from reaching the plant soil and stimulating germination of dormant weed seeds, and which can insulate the soil from contact with drying breezes.
A variety of such materials or "mulches" have in the past been used for the purpose, including leaves, straw, peat moss and the like. Generally speaking, these materials function well in blocking light and in preventing the escape of ground moisture; however, they have the distinct disadvantage of being relatively quick to compact and decompose, at which point they become substantially ineffective with respect to their intended purpose.
Recognizing these disadvantages, other methods for mulching plants have been proposed. Among these may be mentioned, for example, the use of sheets of opaque plastic film which are perforated at intervals so that plantlets can be inserted therethrough and rooted in the soil beneath. While mulch films of the type described are widely used in commercial farming operations where they particularly lend themselves to mulching row crops, they have an unavoidable artificial look, and therefore, are unsightly, particularly in instances where a more natural appearance of the landscape is desired.
In recent years, the forest industry has provided alternative mulches in the form of tree bark materials obtained as byproducts from lumbering operations. One variety of these materials takes the form of bark chips that can be spread where needed to provide an attractive ground cover, and which serve as a weed inhibitor and a moisture conservator. However, wood chips have the disadvantage that they also degrade with the passage of time, losing their attractiveness and becoming a refuge for noxious pests including termites, carpenter ants, and other harmful insects.